During assembly work in a manufacturing process of a turbine or in maintenance of a turbine (replacement work of a vane constituting a part of a blade ring, for example), assembly accuracy of a ring-shaped assembly is important. This ring-shaped assembly is constituted of a blade ring that retains the vane, and a retaining ring that is fixed to an inner circumferential side of the vane and retains a seal ring.
During this work, the blade ring and the retaining ring are positioned (adjusted for coaxiality) using a measurement device for a ring-shaped assembly. At this time, when the positioning of the blade ring and the retaining ring is inappropriate, a gap between the seal ring and a seal fin becomes inappropriate, and sufficient sealability is not achieved. Further, rubbing (contact between a rotating section and a stationary section of a turbine) may occur during rotor rotation due to an eccentricity of the seal ring.
Examples of conventional measurement devices for a ring-shaped assembly include the device described in Patent Document 1, for example. As illustrated in FIG. 6, a measurement device 101 is a device that, in a ring-shaped assembly 60 that includes a blade ring 61, a retaining ring 62, and a vane 63, ensures the assembly accuracy of the retaining ring 62 with respect to the blade ring 61 by measuring a relative position in a radial direction of the retaining ring 62 with respect to the blade ring 61.
In the positioning work using the measurement device 101, a distance between a reference point on the blade ring 61 side and a measurement point on the retaining ring 62 side is measured at a plurality of points on the blade ring 61. In the positioning work using the measurement device 101, an attachment position of the retaining ring 62 with respect to the blade ring 61 is finely adjusted on the basis of this measured value.
The measurement device 101 includes a base section 106, a shaft section 107, and a probe section 108. During measurement, the base section 106 is disposed on an outer circumferential side edge part 61a of the blade ring 61, and defines the reference point on the blade ring 61 side. The shaft section 107 is fixed to and arranged on the base section 106, and extends to an inner side in the radial direction of the blade ring 61 during measurement. The probe section 108 includes a dial gauge 28 attached to a tip of the shaft section 107, and defines the measurement point on the retaining ring 62 side.